Use single-arg form of signal to re-throw an error

Emacs 31.0.t0 supports this since [1: a1358530f53], which also adds
`error-type-p'.  So we check whether that exists to determine which
form we can use.

1: 2026-03-10 a1358530f533a1151c7207e1ad634b1b9fae5a91
   Improve the error API

Author: tarsius

lisp/transient.el

@@ -135,7 +135,9 @@ from Emacs commit e680827e814e155cf79175d87ff7c6ee3a08b69a."
          ,(macroexp-progn body))
      ((debug error)
       (transient--emergency-exit ,id)
-      (signal (car err) (cdr err)))))
+      (static-if (fboundp 'error-type-p) ; since Emacs 31.1
+          (signal err)
+        (signal (car err) (cdr err))))))
 
 (defun transient--exit-and-debug (&rest args)
   (transient--emergency-exit :debugger)